The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 209
n a shelf at the back of theboard. (A view of one of these fasteners in part section isshown in Fig. 211.) Each of the cords is drawn straight, andkept taut by a brass pulley, to which is attached a lead weight.The cords and plugs used on boards on which 5-pointsubscribers jacks are used, need only… … Fig. 211.—Scale EXCHANGE SWITCH-BOARDS 185 board, 2-way plugs and cords only are needed. For possiblefuture multiple working of the boards it is also usual toemploy an operators set which is differentially wound, andwhich has the centre point of the receiver connected to earth(as shown at R of Fig.…
Telephone
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